1. Field of the Invention
The invention relates to the field of semiconductor components. In particular, it relates to a controllable power semiconductor component in which
a plurality of differently doped layers are disposed between two main electrodes;
a control electrode is provided for controlling the component;
the component is subdivided into a plurality of parallelconnected individual elements disposed adjacently to one another;
a control contact is allocated to each individual element, and
the control contacts of the individual elements are connected to a common gate and, together, form the control electrode.
2. Discussion of Background
Controllable power semiconductor components in the form of gate turn-off (GTO) thyristors are gaining increasing importance in power electronics because of their simplified gate drive.
Such GTO thyristors for high switching capacities typically consist of a large number (100 . . . &gt;1000) of individual elements, that is to say individual thyristors or segments, gate-driven independently of one another, which are disposed adjacently to one another and operate in parallel mode.
The current carrying capability of the total component is greatly determined by the different behavior of the individual elements. Thus, it is known, in particular, that the dissipation capacity of an elementary single thyristor can be higher by more than a power of ten than the average dissipation capacity of a larger group of individual elements (see, for example, FIG. 7 in the article by T. Nagano et al. "A snubber-less GTO"Z; Power Electronics Specialists Conf., June 1982, Cambridge/Mass., USA).
The maximum turn-off current of a GTO thyristor of a given size depends, on the one hand, on a scattering of the semiconductor characteristics on the large-are Si substrate. In this regard, the lowest possible scatter and thus a maximized turn-off current can be achieved by careful process control, for example bvy using irradiation processes for doping and adjustment of service life (see A. Jaecklin and B. Adam, "Gate turn-off thyristors with near-perfect technology", Int. Electron Devices Meeting, Los Angeles, December 1986).
On the other hand, the distribution of the firing current to all individual thyristors of a GTO component is nonuniform for geometric reasons because the resistance obtained in the feedlines constructed as coherent layer of metallization is of different magnitude in the case of individual elements having different spacing from the gate or firing connection.
In German Patent Specification No. 3,134,074, it has been proposed in the case of a GTO thyristor having individual elements arranged in concentric rings to eliminate said geometrically-induced nonuniformities in the gate drive by supplying the control current via an annular low-resistance link extending between the concentric rings of the individual elements. This link is inserted into a compound electrode plate which is in contact with the component and must be manufactured with considerable expenditure and high accuracy.
Apart from that, its effectiveness is void as soon as there are more than two concentric rings of individual elements.
In addition, this type of solution does not offer any possibility to eliminate the uneven control current distribution along an individual element itself.